The identity and topographic location of ocular inflammatory, degenerated, and tumor cells and their products in patient specimens and animal samples are analyzed by routine pathology, pathophysiology, immunohistochemistry, and molecular pathology. The application of cutting-edge technology such as microdissection combined with molecular techniques such as PCR, RT-PCR, and RFLP, allows us to provide more accurate pathological diagnosis (assessment) of the disease, and guide us in selecting an appropriate therapy for the patient. We generate and/or apply what we learn from various animal models with ocular disorders, so we can know the mechanisms of different ocular diseases. Using these animal models we can also access the efficacies of different therapeutic agents for various ocular diseases. This helps us to better understand disease pathogenesis and to better select therapies targeting specific diseases. In FY2008, we continued and accomplished the following in our research:[unreadable] [unreadable] 1. Ocular Lymphoma and Adnexal Tumors: [unreadable] [unreadable] We continue to confirm elevation of interleukin-10 in ocular fluids in patients with primary intraocular B-cell lymphoma and IgH gene rearrangements of ocular B-cell lymphoma cells. Chemotherapy regimens with high dose methotrexate are recommended for primary CNS lymphoma. Intraocular chemotherapy has the advantage of limited side effects and has been shown to be useful in primary intraocular lymphoma patients. We found that alterations in the transport of methotrexate across the cellular membrane might contribute to resistance following repeated intravitreal injection. [unreadable] [unreadable] The vast majority of primary intraocular lymphomas are malignant B-cells, while intraocular T-cell lymphomas are rare. We reported a case of metastatic T-cell lymphoma to the eye and demonstrated the utility of immunophenotyping and molecular analysis using microdissection and PCR, as critical adjunctive studies in patients presenting with masquerade syndrome. Vitreoretinal involvement, with no uveal involvement, was seen in this case, similar to many ocular metastatic T-cell lymphomas in the literature. This is intriguing since the uvea, rather than the retina, is the typical ocular tissue invaded in the majority of metastatic tumors, including systemic B-cell lymphoma. [unreadable] [unreadable] We also explore the role of infectious microorganisms (human papilloma virus, HIV, human herpes simplex virus-8, Helicobacter pylori, Chlamydia and hepatitis C virus) in ocular adnexal neoplasms. Multiple organisms may play a role in the etiology of certain ocular adnexal neoplasms by acting through similar mechanisms of oncogenesis, including chronic antigenic stimulation and the action of infectious oncogenes. However, similar to other human malignancies, the ultimate role of infectious agents in ocular adnexal neoplasms is most likely as a cofactor to the other genetic and environmental risk factors. [unreadable] [unreadable] 2. Molecular Pathology of Age-Related Macular Degeneration (AMD): [unreadable] [unreadable] While the clinical and histopathological features of AMD are well characterized, its etiology and pathogenesis remain unclear. Recent discoveries suggest a role for immunologic processes in AMD pathogenesis, including extracellular deposits (drusen) inside the Bruch membrane and beneath the retinal pigment epithelium (RPE), recruitment of macrophages (M2) for clearance of these deposits, complement activation, recruitment of tissue-destructive macrophages (M1), microglial activation and accumulation, and proinflammatory effects of chronic inflammation by microorganisms such as Chlamydia. Further studies are necessary to clarify the precise mechanisms and time course underlying AMD development and, in turn, develop novel therapies for the prevention and treatment of AMD. [unreadable] [unreadable] 3. New Pathology and Pathogenesis of Ocular Diseases: [unreadable] [unreadable] We reported a sizeable decrease of cluster expression in ocular hemangioblastomas associated with von Hippel-Lindau disease (VHL). Clusterin has potential important functions in tumor suppression by VHL protein, and thus may become a novel biomarker in ocular VHL tumors. We also found high vascular endothelial growth factor levels in retinal neovascularization as a manifestation of ocular VHL lesion. We detected serum anti-retinal autoantibodies in acute annular outer retinopathy. We provided the histopathologic evidence, for the first time, that fludarabine (a purine analog) directly induce toxicity to retinal ganglion and bipolar cells causing a rapidly progressive blindness. [unreadable] [unreadable] 4. Experimental Models for Various Ocular Diseases: [unreadable] [unreadable] We proved that Ccl2-/-/Cx3cr1-/- (DKO) mice showed a broad spectrum of AMD pathologies with early onset and high penetrance and possibly imply a role for certain inflammatory molecules, A2E, and endoplasmic reticulum proteins in AMD pathogenesis. The DKO mice present similar immunopathological profiles. Both innate and adaptive immunities play an important role in DKO retinal degeneration. [unreadable] [unreadable] In collaboration with Drs. Caspi, Gery, Hooks, and Nussenblatt of the NEI, and Dr. Restifo of the NCI, several new modes and mechanisms of ocular inflammation and immunotherapy in melanoma have been discovered and published. These are further described in their annual reports.